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International audience; Mg 3 (BH 4) 4 (NH 2) 2 compound was synthesized through the investigation of the Mg(BH 4) 2-Mg(NH 2) 2 phase diagram; its crystal structure was solved in a tetragonal unit cell with the space group I4̅. Interestingly, Mg 3 (BH 4) 4 (NH 2) 2 has a high thermal stability with a decomposition temperature above 190°C and exhibits a high Mg 2+ ionic conductivity of 4.1 × 10 −5 S•cm −1 at 100°C with a low activation energy (0.84 eV). The reversible Mg deposition/stripping was demonstrated at 100°C when using Mg 3 (BH 4) 4 (NH 2) 2 as solid electrolyte. Thus, Mg 3 (BH 4) 4 (NH 2) 2 is a compound that could help to develop rechargeable Mg-ion solid-state batteries.

The organic–inorganic hybrid non-centrosymmetric material [(C 2 H 5 ) 4 N] 2 ZnI 3.86 Cl 0.14 has been studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), dielectric and transport measurements. In analogy with the corresponding tetraiodo-zincate analogue, the material crystallizes at room temperature in the tetragonal system, space group P 4 2 1 m (No. 113), with lattice parameters a = 13.743(6) and c = 14.785(10) A. DSC and XRD characterizations pointed out the occurrence of two phases transitions, one of second order at about 290 K and the other of the first order at T = 451 K. The former is related to an electrical transition from insulating to thermally activated transport mechanism displaying clear hints of ionic conduction, the latter leads to a phase showing the typical features of plastic crystals in its powder XRD pattern. The pattern was indexed by an orthorhombic cell, a = 15.724(1), b = 17.907(1) and c = 10.585(1) A, and a reliable model was found and refined in the Pna2 1 space group. The model consists of ordered tetrahedral ZnCl 4 2− units intercalated by fully disordered tetraethylammonium cations.

Solid Oxide Fuel Cells (SOFCs) are a promising technology that can provide efficient and clean energy production. The general barriers hindering their market entry are durability, i.e. resistance to aging, and costs. In parallel to the deeper insight into the different degradation sources and improved understanding of ageing factors and their interactions, work towards higher accuracy for the assessment and monitoring of real-world fuel cell ageing in necessary. The requirements for operational stability formulate the parameter “degradation rate” (DR). Most often long term durability tests are performed at constant current load and the decrease of the voltage is used for its definition. In this work a new approach based on analysis of the volt-ampere characteristics, named Differential Resistance Analysis (DRA), is presented. It operates with the differential resistance, i.e. with the derivative of the voltage in respect to the current (dU/dI = Rd) which is more sensitive to small deviations and thus increases the sensitivity of the analysis. Two performance indicators are derived (Rd, min and ∆U*) with differing selectivity: ∆U* is more sensitive to activation losses and Rd, min - to transport hindrances. The application of the DRA is demonstrated on examples from measurements in fuel cell and in reverse (fuel cell/electrolyzer) mode, as well as on modeling data. The results show that the method is at least 10 times more sensitive to DR evaluation in comparison with the classical approach.

In this work, a new type of addition reaction between La(BH4)3 and LiX, X = Cl, Br, I, is used to synthesize LiLa(BH4)3Cl and two new compounds LiLa(BH4)3X, X = Br, I. This method increases the amounts of LiLa(BH4)3X and the sample purity. The highest Li-ion conductivity is observed for LiLa(BH4)3Br, 7.74 × 10-5 S/cm at room temperature (RT) and 1.8 × 10-3 S/cm at 140°C with an activation energy of 0.272 eV. Topological analysis suggests a new lithium ion conduction pathway with two new different types of bottleneck windows. The sizes of these windows reveal an opposite size change with increasing lattice parameter, that is, increasing size of the halide ion in the structure. Thus, we conclude that the sizes of both windows are important for the lithium ion conduction in LiLa(BH4)3X compounds. The lithium ion conductivity is measured over one to three heating cycles and with different contacts (gold or carbon) between the electrodes and the electrolyte. Moreover, 11B MAS NMR is used to verify the contents of the samples, whereas thermogravimetric analysis shows 4.8 and 3.6 wt % of hydrogen release for LiLa(BH4)3Cl and LiLa(BH4)3Br in the temperature range RT to 400°C. (Graph Presented).

The 70-year history of scientific endeavor of solid state ionics research in Japan is reviewed to show the contribution of Japanese scientists to the basic science of solid state ionics and its applications. The term ‘solid state ionics’ was defined by Takehiko Takahashi of Nagoya University, Japan: it refers to ions in solids, especially solids that exhibit high ionic conductivity at a fairly low temperature below their melting points. During the last few decades of exploration, many ion conducting solids have been discovered in Japan such as the copper-ion conductor Rb4Cu16I7Cl13, proton conductor SrCe1–xYxO3, oxide-ion conductor La0.9Sr0.9Ga0.9Mg0.1O3, and lithium-ion conductor Li10GeP2S12. Rb4Cu16I7Cl13 has a conductivity of 0.33 S cm–1 at 25 °C, which is the highest of all room temperature ion conductive solid electrolytes reported to date, and Li10GeP2S12 has a conductivity of 0.012 S cm–1 at 25 °C, which is the highest among lithium-ion conductors reported to date. Research on high-temperature proton conducting ceramics began in Japan. The history, the discovery of novel ionic conductors and the story behind them are summarized along with basic science and technology.

Solid inorganic and polymeric electrolytes have the potential to enable rechargeable batteries with higher energy densities, compared to current lithium-ion technology, which uses liquid electrolyte. Inorganic materials such as ceramics and glasses conduct lithium ions well, but they are brittle, which makes incorporation into a battery difficult. Polymers have the flexibility for facile use in a battery, but their transport properties tend to be inferior to inorganics. Thus, there is growing interest in composite electrolytes with inorganic and organic phases in intimate contact. This article begins with a discussion of ion transport in single-phase electrolytes. A dimensionless number (the Newman number) is presented for quantifying the efficacy of electrolytes. An effective medium framework for predicting transport properties of composite electrolytes containing only one conducting phase is then presented. The opportunities and challenges presented by composite electrolytes containing two conducting phases are addressed. Finally, the importance and status of reaction kinetics at the interfaces between solid electrolytes and electrodes are covered, using a lithium-metal electrode as an example.

As an ionic conductive functional layer of intermediate temperature solid oxide fuel cells (ITSOFC), samarium-doped ceria (SDC)–LiNaSO4 nano-composites were synthesized by a sol–gel method and their properties were investigated. It was found that the content of LiNaSO4 strongly affected the crystal phase, defect concentration, and conductivity of the composites. When the content of LiNaSO4 was 20 wt%, the highest conductivity of the composite was found to be, respectively, 0.22, 0.26, and 0.35 S cm−1 at temperatures of 550, 600, and 700 °C, which are much higher than those of SDC. The peak power density of the single cell using this composite as an interlayer was improved to, respectively, 0.23, 0.39, and 0.88 W cm−2 at 500, 600, and 700 °C comparing with that of the SDC-based cell. Further, the SDC–LiNaSO4(20 wt%)-based cell also displayed better thermal stability according to the performance measurements at 560 °C for 50 h. These results reveal that SDC–LiNaSO4 composite may be a potential good candidate as interlayer for ITSOFC due to its high ionic conductivity and thermal stability.

The viability of water gas shift catalytic system for mobile application passes through obligatory reactor volume reduction, achieved normally by using less charge of more efficient catalyst. Completely new concept for catalyst design is proposed: a catalytic system including classically reported WGS catalysts of different nature or active phase (Cu, Pt or Au) mechanically mixed with an ionic conductor. The influence of the later on catalyst activity is studied and discussed, more precisely its effect on the rate of the reaction-limiting step and catalysts’ efficiency. It is demonstrated with this study, that the presence of an ionic conductor in contact with a WGS catalyst is essential for the water supply (dissociation and transport), thereby potentiating the water activation step, whatever the mechanism and catalyst overall performance., We acknowledge financial support for this work from the Spanish Ministerio de Economía y Competitividad (MINECO) (ENE2015-66975-C3-2-R).

This work reports on the investigation of CO 2 selective membranes for pre-combustion and post- combustion processes, in which CO 2 is extracted from multi-component gas streams at intermediate temperature (400 – 600 °C). The dual-phase membranes developed in this work are designed as a porous oxide ion conducting ceramic matrix, which is infiltrated with a molten carbonate phase. Both ex-situ and in-situ characterization methods were used to study disk shaped and tubular membranes. The gas transport properties of disk-shaped membranes were further investigated under various operating conditions relevant for both post-combustion and pre-combustion applications.

In order to investigate why crystal symmetry lowers with increasing temperature by phase transition of TII–III (=369 K) in Cs3H(SeO4)2, in spite of the fact that crystal symmetry in the high-temperature phase of many ionic conductors becomes higher by the phase transition, we have studied the relation between the change in crystal symmetry and the appearance of proton motion. It was found from the analysis of domains based on crystal structure that the number of possible geometrical arrangement of hydrogen bond in phase II becomes two times larger than that in phase III, derived from the lowering of crystal symmetry with increasing temperature. These results indicate that the lowering of crystal symmetry in phase II appears by the increase of the number of geometrical arrangements and by the enhancement of the flexibility of hydrogen bond. Considering that the enhancement of the flexibility of hydrogen bond yields mobile proton in phase II, it is deduced that mobile proton in phase II appears in exchange for the lowering of crystal symmetry at II–III phase transition.

Rapidly growing attention is being recently directed towards the investigation of the ionic conducting properties of oxide film hetero-structures. Experimental evidence has been reported showing that interfacial phenomena at hetero-phase interfaces give rise to faster ion conduction pathways than the bulk or homo-phase interfaces. Nonetheless, a deeper understanding of the interface transport properties is still needed to exploit these effects. In this work we have investigated the growth mechanism of different superlattices fabricated by pulsed laser deposition (PLD) coupling doped and undoped cerium and zirconium oxides. Single crystalline MgO wafers were selected as deposition substrates. The superlattice structures were obtained by means of a thin buffer layer of SrTiO3 (STO). The growth mechanism was investigated by reflection high energy electron diffraction (RHEED) and X-ray diffraction (XRD) analyses.

Ionic liquid (IL) based gel polymer electrolytes (GPEs) are being investigated extensively at present as substitutes for conventional GPEs based on a polymer, a salt and solvents. The main reason behind this is the drawbacks in usage of solvents. IL based GPEs have been employed for energy storage devices such as batteries and super capacitors due to their interesting mechanical, physical and electrochemical properties. This study focused on synthesis preparation and characterization of an IL based GPE consisting of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-co-HFP), zinc trifluoro metha -nesulfonate (Zn(CF3SO3)2 - ZnTF) and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (1E3MITF). Thin film samples were prepared using solvent casting method. The optimized composition was found to be 1 PVdF-co-HFP: 1 1E3MITF: 3 ZnTF (by weight basis). This mechanically stable, thin film has the maximum room temperature conductivity of 7.42×10-3 S cm-1. Conductivity variation with temperature follows Vogel - Tamman - Fulcher (VTF) behavior confirming the relation of conductivity mechanism with the free volume theory. The IL based GPE is a purely an ionic conductor having a considerable anionic contribution. It shows stability up to 2.5 V which is very much convenient from a practical point of view. Oxidation and reduction of Zn takes place at the potentials of 0.5 V and –0.5 V, respectively. In addition, Zn platting and stripping occurs only on the Zn electrodes but not on the stainless steel (SS) electrodes. Impedance measurements taken for the GPE continuously for a long period of time exhibited a satisfactory stability with Zn electrodes.

Memristive properties of thin film copper oxides with different grain sizes were characterized using tunneling atomic force microscopy (TUNA) and optical reflection measurements. The thin films containing copper ions of different chemical states were prepared by thermal oxidation of metallic copper thin films, deposited via magnetron sputtering onto silicon wafer substrates at an elevated temperature for various lengths of time. The TUNA measurements showed a memristive hysteresis in the I-V curves under an applied bias profile with an initial bias of -3.5V, a ramp up to 3.5V, and subsequent return to -3.5V. Histogram analysis of the barrier height distribution for the forward and backward bias indicated that the barrier height fluctuates in a narrow range of bias voltages that are related to electrochemical potentials for oxidation/reduction of copper ions. Changes in chemical state of copper atoms were identified by optical reflectance measurements in UV-VIS-NIR wavelength regions. The growth of the thin films, including grain size, were characterized by topographic AFM imaging and changes in optical absorption bands due to the quantum size confinement effects. The fluctuations in the I-V measurements are theorized to be results of electrochemical changes as mobile ions migrate along grain boundaries due to heterogeneities in grain orientation/structure. A subtle periodic behavior and the variability of the I-V data suggest a correlation with grain size distribution. The asymmetric distribution in the barrier height may indicate that a different probability for injecting an electron in and withdrawing an electron from the films.

[ES] En este trabajo se discuten los resultados obtenidos en el estudio de fibras eutéticas de ZrO2(Y2O3)-Al2O3 crecidas por fusión zonal mediante láser. Las diferentes condiciones de crecimiento tienen un importante efecto en la microestructura. Se ha medido la conductividad eléctrica de las muestras y relacionado los valores obtenidos con la microestructura y composición de las fibras. Las mayores conductividades conseguidas son de 6.8x10-3 Scm-1 a 900ºC., [EN] The results obtained in the growth of eutectic ZrO2(Y2O3)-Al2O3 fibres by laser floating zone are discussed. The variation of the growth conditions have an important effect on the observed microstructures. Conductivity measurements were carried out at high temperature indicating that a relationship between these values and the microstructure and composition of the samples can be established. The highest conductivity obtained was 6.8x10(-3) Scm-1 at 900ºC., Este trabajo ha sido financiado por la CICYT (MAT97-0673-C02-01).

We focus on the features of spectra and diagrams of states obtained via exact diagonalization technique for finite ionic conductor chain in periodic boundary conditions. One dimensional ionic conductor is described with the lattice model where ions are treated within the framework of "mixed" Pauli statistics. The ion transfer and nearest-neighbour interaction between ions are taken into account. The spectral densities and diagrams of states for various temperatures and values of interaction are obtained. The conditions of transition from uniform (Mott insulator) to the modulated (charge density wave state) through the superfluid-like state (similar to the state with the Bose-Einstein condensation observed in hard-core boson models) are analyzed., 7 pages, 5 figures

A general, efficient and experimentally simple method for the synthesis of covalently crosslinked class II hybrid polymers based on PolyEtherEtherKetone (PEEK) with a high degree of sulfonation (DS = 0.8) was performed. The synthetic strategy foreseen two steps: the first one, direct sulfonation, led to the introduction of sulfonic acid groups and to the formation of sulfone bridges among repeat units. The second step, lithiation and silylation, led to the formation of covalent bonds between the organic backbone and Si(OH)3 moieties. The materials were characterized by 1H NMR Spectroscopy, ATR/FTIR Spectroscopy, Thermogravimetric Analysis (TGA) and Mass Spectrometry. Preliminary proton conduction measurements in dry conditions were performed. The introduction of silicon groups in the system improved thermal stability.